A simple and regiospecific aminohydroxylation of olefins by photoredox catalysis has been developed. N-protected 1-aminopyridinium salts are the key compounds and serve as amidyl radical precursors by the action of Ir photocatalysts, fac-[Ir(ppy)3] and [Ir(ppy)2 (dtbbpy)](PF6) (ppy=2-pyridylphenyl, dtbbpy=4,4'-di-tert-butyl-2,2'-bipyridine). The present photocatalytic system allows for synthesis of vicinal aminoalcohol derivatives from olefins with various functional groups under mild reaction conditions with easy handling.